Americans for Prosperity, which is not required to disclose its donors while spending more than $20 million on ads trying to oust President Obama, accidentally provided more detail than required on where exactly it was spending its millions last week. That is, until the group realized that even that information is not required by the Federal Election Commission.

When it filed a report on Aug. 8 with the FEC detailing its TV ad buys for the week, the Koch brothers-funded organization included a state-by-state breakdown of how much they spent in 11 swing states. That level of detail is actually not required for the presidential race because the Federal Election Commission considers it a national-level race.

The ad buys were the first of a new campaign that totals $25 million, its biggest ad drop yet in the 2012 race.

Caught revealing more than they had to, Americans for Prosperity amended the filing about a week later to omit the state-by-state breakdown. But the old report remains in the FEC system.

Perhaps the FEC faux pas is due to the fact that the group is out of practice reporting its spending. Until just recently, it wasn't required to disclose ad buys it made characterizing President Obama as a disappointment. Because those ads were aired more than 30 days before the nominating conventions and 60 days before the general election, no FEC reports are necessary.

But with the Democratic convention coming up in less than three weeks, the group has to start reporting its anti-Obama ads–albeit its donors can remain a secret.

The misstep at least provided some information that the public otherwise wouldn't know: Where is the group spending the most and exactly how much it is spending? That information is only currently available through estimates by the ad-tracking company Kantar/CMAG, but purchasing its data is expensive. The Washington Post, which has an arrangement with Kantar/CMAG, has been making some of that information available.

The original report revealed a $6.4 million buy over 11 states in one week alone, with the biggest hauls going to Florida ($1.2 million), Ohio ($918,797), Pennsylvania ($775,748) and North Carolina ($741,030). That order reflects not only the importance of winning the vote in those states but also their expensive media markets. The other states were Colorado, Iowa, Minnesota, New Mexico, Nevada, Virginia and Wisconsin.

Only two outside groups have spent more money on presidential race ads: The Karl-Rove founded Crossroads GPS and the super PAC backing Mitt Romney called Restore Our Future, according to the Washington Post.

As of press time, Americans for Prosperity had not returned requests to comment.